Effect of degree of substitution of carboxymethyl starch on diaspore depression in reverse flotation

Carboxymethyl starchs（CMS） with low and high degrees of substitution（CMSL and CMSH in short,respectively） were employed as depressants of diaspore in cationic reverse flotation using dodecylamine（DDA） as collector.The effect of degree of substitution of CMS on its depression performance was examined and the interaction mode and behavior were investigated in a comparative manner.Micro-flotation test showed that CMSL exhibited better performance in depressing diaspore than CMSH in a broad pH range.The adsorption of CMS on diaspore was studied by adsorption test,zeta potential measurement,and atomic force microscopy.It was found that CMSH corresponds to lower adsorption amount,thinner adsorption layer,and more negative charge than CMSL,resulting from the more chelating sites brought by the high degree of substitution.The surface tension measurement and DDA adsorption test further revealed that CMSL/DDA system gives a better depressing performance benefiting from the trapping effect by enveloping some DDA molecules inside the loop chains,while CMSH/DDA system is likely considered a quasi-surfactant.

Effect of sodium alginate on reverse flotation of hematite and its mechanism

Given the gradual increase in the chlorite content of hematite ores, pulp properties seriously deteriorate during flotation. The traditional anion reverse flotation of hematite cannot effectively eliminate the effects of chlorite, leading to a significant decrease in the total Fe(TFe) grade of the concentrate. In this work, the effect of sodium alginate on the reverse flotation of hematite was systematically investigated. Flotation tests of artificially mixed ores were conducted, and the results showed that sodium alginate can significantly improve the removal rates of quartz and chlorite. The adsorption measurements, infrared spectroscopy, and contact angle tests demonstrated that sodium alginate adsorbs on the quartz surface by chelating with calcium ions, thereby weakening the steric hindrance of oleate ions and increasing the adsorption capacity of sodium oleate to ultimately improve the removal rate of quartz. Furthermore, owing to its lower density and fine particle size, chlorite is easily entrained into the foam layer. Sodium alginate dramatically increases the liquid-to-gas ratio of the foam layer by increasing pulp viscosity, thereby increasing the entrainment rate of chlorite and finally improving its removal rate. The core content of this thesis bears significance in improving the Fe grade in the reverse flotation of chlorite-containing hematite.

Recovery of molybdenum and copper from porphyry ore via iso-flotability flotation

A copper-molybdenum iso-flotability flotation process has been developed to efficiently improve the recovery ofmolybdenite from Duobaoshan porphyry Cu-Mo ores.The effects of flotation approach,type of collector,feed particle sizedistribution,rougher pH value and reagent dosage on the recovery of molybdenite were evaluated systematically.The results suggestthat compared with kerosene and diesel oil,transformer oil has stronger dispersion capability in water media and better flotationselectivity for molybdenite,providing a higher molybdenum recovery under low reagent dosage.Moreover,compared with bulkflotation approach,the iso-flotability flotation approach using transformer oil as a collector can obtain superior Mo recovery(90.77%)and grade(0.80%)in the cleaner concentrate,and increase the Mo recovery and grade by over18%and5%in the final Moconcentrate,respectively.The results of commercial flotation further indicate that the iso-flotability flotation approach is a rationaland effective route to beneficiate the porphyry Cu-Mo ores.

Effect and mechanism of siderite on reverse flotation of hematite

The effects of siderite on reverse flotation of hematite were investigated using micro flotation, adsorption tests, and Fourier transform infrared spectroscopy. The flotation results show that interactions between siderite and quartz are the main reasons that siderite significantly influences the floatability. The interactions are attributed to dissolved siderite species and fine siderite particles. The interaction due to the dissolved species is, however, dominant. Derjaguin-Landau-Verwey-Overbeek（DLVO） theoretical calculations reveal that adhesion on quartz increases when the siderite particle size decreases and that fine particles partly influence quartz floatability. Chemical solution calculations indicate that the dissolved species of siderite might convert the surface of active quartz to CaCO_3 precipitates that can be depressed by starch. The theoretical calculations are in good agreement with the results of adsorption tests and FTIR spectroscopy and explain the reasons why siderite significantly influences reverse flotation of hematite.

Effect of hydroxamic acid polymers on reverse flotation of bauxite

The effect of hydroxamic acid starch (HAS) and hydroxamic acid polyacrylamide (HPAM) on the flotation of diaspore and kaolinite was investigated by flotation test. It is found that HAS depresses diaspore but activates kaolinite in acidic pulp,while HPAM activates both diaspore and kaolinite in the pH range of 2.010.5. The measurement of zeta potential shows that both HAS and HPAM can increase zeta potential of negatively charged diaspore, which indicates the existence of chemical bonding or hydrogen bonding between the reagents and diaspore. By covering the collector dodecyl amine(DDA) on diaspore surface,HAS increases the hydrophilicity of minerals and depresses the flotation of diaspore,however HPAM activates the flotation of diaspore by increasing the adsorption of DDA on diaspore surface.

A novel cationic collector for silicon removal from collophane using reverse flotation under acidic conditions

We analyzed a novel cationic collector using chemical plant byproducts,such as cetyltrimethylammonium bromide(CTAB)and dibutyl phthalate(DBP).Our aim is to establish a highly effective and economical process for the removal of quartz from collophane.A microflotation test with a 25 mg·L^(−1)collector at pH value of 6-10 demonstrates a considerable difference in the floatability of pure quartz and fluorapatite.Flotation tests for a collophane sample subjected to the first reverse flotation for magnesium removal demonstrates that a rough flotation process(using a 0.4 kg·t−1 new collector at pH=6)results in a collophane concentrate with 29.33wt%P_(2)O_(5)grade and 12.66wt%SiO2 at a 79.69wt%P_(2)O_(5)recovery,providing desirable results.Mechanism studies using Fourier transform infrared spectroscopy,zeta potential,and contact angle measurements show that the adsorption capacity of the new collector for quartz is higher than that for fluorapatite.The synergistic effect of DBP increases the difference in hydrophobicity between quartz and fluorapatite.The maximum defoaming rate of the novel cationic collector reaches 142.8 mL·min−1.This is considerably higher than that of a conventional cationic collector.

Double reverse flotation process of collophanite and regulating froth action

A new double reverse flotation process was used to beneficiate the Yichang region collophanite of Hubei Province,China. Its final concentrate yield is 67.37%,P2O5 grade is 32.17%,P2O5 recovery is 87.80%,and the main impurities MgO,Fe2O3 and Al2O3 are 0.95%,1.04%,1.36%,respectively.The difficult problem was successfully solved that plentiful froths are bought by the cationic collector reverse flotation in collophanite beneficiation by adding inorganic froth regulator CA to the pulp.The defrothing mechanism was studied through mensurating surface tension and Zeta potential of the pulp after adding CA.It is found that the changing of surface tension and hoisting of Zeta potential may be the main reasons that froths become friable and break up.

Effect of hydroxamic acid starch on reverse flotation desilicate from diasporic bauxite

It is important to depress diaspore effectively in order to remove silicates from diasporic bauxite. A new water soluble polymer hydroxamic acid starch (HA-starch) was prepared. The effects of the product on the diaspore and kaolinite flotation were investigated and its reactive mechanism was studied by zeta potential measurement and FTIR. The results show that HA-starch can depress diaspore while make positive effect on kaolinite flotation at low pH value(pH below 6). The flotation recovery of diaspore was sharply decreased with the increase of concentration of HA-starch. The chemical adsorption of HA-starch on the surface of diaspore was revealed.

Reverse flotation separation on diaspore and kaolinite in the presence of cationic polyacrylamide polymers

Based on the analyses of crystal structures and surface properties of diaspore and kaolinite, an effective diaspore depressant, CPAM(cationic polyacrylamide) polymers was discovered by single minerals tests, separation experiments of artificial mixed minerals, zetapotential and adsorption measurement. The reverse flotation separation on diaspore and kaolinite can be carried out using collector dodecylamine acetate and depressant CPAM under pH 5.5 8.5. On the surfaces of diaspore, there are a large amount of active aluminum atoms. They can bond with -C(O)NH 2 groups in CPAM and make the -CH 2N +(CH 3) 3 groups in CPAM orient toward the outer surfaces of diaspore, which prevents a majority of the dodecylamine cations from adsorbing on diaspore, enhances hydrophilicity of diaspore, and depresses the floatability of diaspore. But for kaolinite, CPAM polymers have little effect on its floatability.

The Role of Flotation Reagents in the Reverse Flotation of Carbonate-Containing Iron Ores

The Influence of pulp pH, dispersants and auxiliary collectors on reverse flotation of carbonate-containing iron ores were explored. Interactions between iron ores and quartz were theoretically analyzed by flotation solution chemistry and DLVO theory. The results indicated that the iron concentrate grade improved sharply when pH increased from 11.0 to 12.0, but changed unobviously when pH was larger than 12.0, which was related to solution chemistry of siderite and interactions among particles. Sodium tripolyphosphate was an effective dispersant and sodium dodecyl sulfate was an effective auxiliary collector of KS-III. Both recovery and grade enhanced by the action of sodium dodecyl sulfate or sodium tripolyphosphate when pH was 12.0.

Flotation of low-grade bauxite using organosilicon cationic collector and starch depressant

The flotation of diaspore and three kinds of silicate minerals, including kaolinite, illite and pyrophyllite, using an organosilicon cationic surfactant (TAS101) as collector and starch as depressant was investigated. The results show that both diaspore and aluminosilicate minerals float readily with organosilicon cationic collector TAS101 at pH values of 4 to 10. Starch has a strong depression effect for diaspore in the alkaline pH region but has little influence on the flotation of aluminosilicate minerals. It is possible to separate diaspore from aluminosilicate minerals using the organosilicon cationic collector and starch depressant. Further studies of bauxite ore flotation were also conducted, and the reverse flotation separation process was adopted. The concentrates with the mass ratio of Al2O3 to SiO2 of 9.58 and Al2O3 recovery of 83.34% are obtained from natural bauxite ore with the mass ratio of Al2O3 to SiO2 of 6.1 at pH value of 11 using the organosilicon cationic collector and starch depressant.

Comparative studies on flotation of aluminosilicate minerals with Gemini cationic surfactants BDDA and EDDA

Gemini quaternary ammonium salt surfactants, butane-a, co-bis（dimethyl dodeculammonium bromide） （BDDA） ethane-a, fl-bis（dimethyl dodeculammonium bromide） （EDDA） were adopted to comparatively study the flotation behaviors of kaolinite, pyrophyllite and illite. It was found that three silicate minerals all exhibited good floatability with Gemini cationic surfactants as collectors over a wide pH range, while BDDA showed a stronger collecting power than EDDA. FTIR spectra and zeta potential analysis indicated that the mechanism of adsorption of Gemini collector molecules on three silicate minerals surfaces was almost identical for the electronic attraction and hydrogen bonds effect. The theoretically obtained results of density functional theory （DFT） at B3LYP/6-31G （d） level demonstrated the stronger collecting power of BDDA presented in the floatation test and zeta potential measurement.

Flotation de-silicating from diasporic-bauxite with cetyl trimethylammonium bromide

Using cetyl trimethylammonium bromide （CTAB） as collector, the flotation de-silicating from diasporic-bauxite was investigated. And the Zeta potentials and contact-angles of silicate minerals and diaspore were also stu-（died.）The results show that in the presence of 2×10-4 mol·L-1CTAB, the surface charges of pyrophyllite, kaolinite and illite become more positive, and the contact angles of these three silicates also increase evidently in the pH range of 2-8, but the Zeta potentials and contact angles of diaspore change little. So, the floatability of the four minerals is in the following order: pyrophyllite>kaolinite≈illite>diaspore. The open-circuit flotation results also show that a bauxite concentrate with m（Al2O3）/m（SiO2） over 9.3 and Al2O3 recovery over 76% can be obtained from diasporic-bauxite ore. The result of XRD of the bauxite concentrate shows that pyrophyllite is easier to be removed from diasporic-bauxite than illite and kaolinite due to its better floatability.

Flotation techniques for separation of diaspore from bauxite using Gemini collector and starch depressant

The floatability of diaspore and three kinds of silicate minerals,including kaolinite,illite and pyrophyllite,by a cationic Gemini surfactant as collector and starch as depressant was investigated as function of reagents concentration and pulp pH.Further studies of artificially mixed minerals and bauxite ore were also detailedly conducted.At last,the pre-desliming reverse flotation separation process was adopted.It can be concluded that the combinational use of a Gemini cationic collector and the starch depressant is effective.The concentrates with Al2O3 to SiO2 mass ratio of 9.66 and the recovery of Al2O3 of 71.73% are obtained from natural bauxite ore(A/S=5.70) at pH value of around 10.

Two-step flotation recovery of iron concentrate from Donganshan carbonaceous iron ore

The flotation of pure and natural carbonaceous iron ore samples in the oleate flotation system was investigated.Starch can depress hematite effectively in a wide pH range,but cannot depress siderite efficiently in neutral conditions.The flotation recovery of pure hematite,siderite,and quartz in the oleate-starch-CaCl2 system is significantly different when the slurry pH varies from 4 to 12.A novel two-step flotation process was developed for the separation of iron concentrate from Donganshan carbonaceous iron ore through which the siderite concentrate is first recovered and the high quality hematite concentrates with relative high iron recovery can be obtained in the second step flotation.The siderite concentrate may be utilized directly or undergo further concentration steps to increase iron grade.

Electrostatic concentration of phosphate flotation concentrate

The concentration of phosphate flotation concentrate with P2O5 grade lower than the commercially acceptable phosphate quality was upgraded in the use of tribo-electrostatic technique. The concentration of the flotation concentrate stream was conducted under both triboelectrification and inductive charging mechanism. Mineralogical analysis reveals that the phosphate ore utilized was dominated mainly by fluorapatite, crandallite, wavellite, and with quartz as the major gangue mineral. Flotations concentrate of about 28.87% P2O5 was obtained from the reverse flotation technique, after conditioning the phosphate ore at 80% passing 150 lm under Lilafloat. Constant parameters such as à6 kV charging voltage, 25 kV separating voltage, inlet air, different charger rotary speed and splitter distances were investigated. Commercially accepted grade of 35.50% P2O5 was attained after the second stage of separation with a recovery of 12.26%, another phosphate product of 34.02% P2O5 and 85.19% was also recovered under the same condition. Single stage of separation also shows a significant increase in the grade of the product obtained, with 33.41% P2O5 and 84.07% recovery achievable. The practicability of tribo-electrostatic separation technique for upgrading flotation concentrates resulted in a significant increase in grade for <150 lm product that do not meet the viable grade.

Aluminum-silicates flotation with quaternary ammonium salts

The zeta potential measurements show that the flotation separation of diaspore from kaolinite, illite and pyrophyllite could be achieved in the range of pH 46.5 with cationic collectors. A special quaternary ammonium salts(DTAL) shows better selectivity than that the dodecyl amine(DDA) does for the flotation of three silicates. The closed circuit flotation results show that the reverse flotation de silicate can be achieved with DTAL as collector, a new inorganic reagent(SFL) as depressant and MIBC as frother to obtain a bauxite concentrate m (Al 2O 3)/ m (SiO 2) >10, Al 2O 3 recovery>86%).

Synthesis of N,N-diethyl dodecyl amine and its flotation properties on bauxite

N, N-diethyl dodecyl amine（DEN12） was synthesized from dodecyl amine, formic acid and acetic aldehyde. The collecting property of DENI2 on diaspore, kaolinite and illite was investigated by flotation test and infrared spectrum. The results show that in the presence of 2.0× 10^-4 mol/L DEN12, the recoveries of kaolinite and illite are all higher than 78% and the recovery of diaspore is 50% in the pH range of 5.5-6.0. The mass ratio of A1203 to SiO2 in concentrate obtained from separation artificial mixture is higher than 10, suggesting that DEN12 can be used as a collector to separate the aluminosilicates from diaspore in bauxite ores at the pulp pH below 8. The measurements of the infrared spectrum approve that the action between aluminosilicates and tertiary amine collector is strong electrostatic adsorption and that of diaspore is weak electrostatic adsorption.

辽宁某铁矿低温捕收剂浮选工艺试验

辽宁某铁矿石选矿厂的弱磁—强磁混合磁选精矿的TFe品位为53.92%,主要铁矿物以磁/赤铁矿的形式存在,主要脉石矿物为石英。该选矿厂现场采用TD-Ⅱ捕收剂进行反浮选,但浮选矿浆温度为40℃,导致资源浪费,为提高生产指标,使用东北大学自主研发的新型含多极性基低温捕收剂DZ对该选厂的混合磁选精矿进行反浮选试验研究。试验考察了捕收剂DZ用量、矿浆pH值、浮选温度、淀粉用量、CaO用量对混合磁选精矿的浮选行为的影响。针对TFe品位为53.92%的混合磁选精矿,采用新型低温捕收剂DZ在浮选温度15±2℃、矿浆pH值9、淀粉用量750g/t、捕收剂DZ用量150g/t,在不添加活化剂的条件下,经过“一粗二精三扫”的浮选闭路试验,可得到TFe品位65.24%、铁回收率93.03%的浮选精矿指标。采用捕收剂TD-Ⅱ在浮选温度40±2℃、矿浆pH值11、淀粉用量900g/t、CaO用量900g/t、捕收剂TD-Ⅱ用量350g/t的条件下,经过“一粗一精三扫”的浮选闭路试验,可得到TFe品位65.47%、铁回收率90.71%的浮选精矿指标。对新型低温捕收剂DZ以及现场药剂TD-Ⅱ体系所得浮选闭路的精矿进行产品检查,通过浮选结果与产品检查对比可发现,新型低温捕收剂DZ是一种高效、选择性高的低温浮选捕收剂,能有效解决选矿厂在反浮选过程中的能源浪费问题,节约选矿成本,提高资源利用效率。

酒钢悬浮焙烧磁铁矿选矿工艺优化研究

对酒钢悬浮焙烧磁铁矿进行了磨矿-选矿工艺优化研究。采用110 mT低场强磁选机预提精、中矿再磨后采用磁选富集抛尾、富集精矿经阳离子反浮选,最终获得TFe品位60.06%、SiO_(2)含量5.17%、金属回收率84.27%的综合精矿;与原工艺指标相比,精矿TFe品位提高了1.96个百分点,金属回收率提高了1.38个百分点,SiO_(2)含量降低了1.06个百分点。